Punch



c. E. MANGE June 13, 1939.

PUNCH Filed May '7, 1938 Patented June 13, 1939,v

Umfrao "STATES PATENT orf-ica PuNcn clarence n. Mange, st. Lani, no., um to Jacken-Evans Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application May 7 1938. Serial No. 206,591

11 Claims. (Cl. 18d-119) This invention relates to punches, and with regard to certain more specific features to a sheet-metal punch. j

Among the several objects of the invention may g be noted the provision of a sheet metal punch which will punch a hole of the proper form in adjacent layers of sheet metal for the reception of so-called sheet-metal fastening screws; the provision of a punch of the class described which gg will avoid undesirable deformation of unbacked sheet metal during the punching operation; and the provision of a punch of the class described which may be operated at a high speed and with littleveiort. Other objects will be in part obli` vious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter op described, and the scope of the lapplication of which will be indicated in the following claims. In the accompanying drawing, in which are illustrated several of various possible embodiments of the invention.

.g5 Fig. 1 is a vertical section of one form of the plumb;

Fig. 2 is a view similar to Fig. 1 showing another form;

Fig. 3 is a bottom plan view of Fig. l;

so Fig. 4 is a fragmentary section showing another form of the invention, parts being shown in elevation; y

Fig. 5 is a view similar to Fig. i showing an- Y other form;

3g Fig. 6 is a horizontal section taken on line 6 6 of Fig. 5;

Fig. 7 is a side elevation, on a reduced scale,

illustrating a step carried out in the use of the form of the invention shown in Fig. 1; and,

40 Fig. 8 is a fragmentary view similar to Fig. 1 showing a punching operation just after co pletion.

Similar reference characters indicate corresponding parts throughout the several views of 45 the drawing.

Much light sheet-metal work requires holding screws for holding adjacent sheets together. In

orderto. make the necessary holes for thesescrews, it is preferable that they be punched so 50 as to obtain a hole with a more or less ragged edge which tends'to hold the metal screw much Heretofore,

firmer than would a drilled hole. the disadvantage of punching holes has been that in many instances it was impossible to back a -given area of sheet metal. with any support ing operation.

against the blow which was used for the punch- As a result. this method is not used. Drilling is slowfcostly, and provides too smooth a holefoi `best holding of the screw. 'I'he present invention provides a punch which 5 will properly make the necessary holes without the requirement of backing means.

.Referring now more particularly to Fig. 1, there is shown atvnumeral I atube which is threaded into a nipple 8. The large end of the 10 nipple 3 carries an extension' 5 which is interioriy flanged for th'e purpose of holding the end Il of a tension spring i5, as shown at i. Around the lower end of the extension is a rubbei' or like friction ring 9. As the drawing 15 shows. the lower end of the ring S extends below the lower end of the extensi 5.

Along-the center of the t be I is a stem II. At the upper end of the stem is fastened a knob I3. Near this upper end is fastened the upper v end of the tension spring I5. The stem I I passes through the spring and at its lower end carries a removable shank i9. The shank I9 is threaded `to the stem il and has a point 2`I which preferably is of pyramidal form rather than conic. Any form of the point I which has angles is preferable to one which does not, for reasons which will appear, although a round form is operative.

Fig. 1 illustrates a first step in the operation 30 of producing a hole in adjacent layers of sheet metal 23. The point 2l is set down exactly where desired. Then the tube I. is pushed down until the frictionring 9 touches the sheet metal 23, or, if desired, the point 2I may be drawn back and 35 the anti-skid device 9 may be initially applied to the sheet metal 23.

Then, the knob I3 is drawn back (Fig. 7) so that the point 2i is positioned as far back as possible in the tube I. Then by4 releasing the 40 knob I3, the assembly comprising knob I3, stem ii and shank I! attains a high velocity before piercing, as shown inV Fig. 8. 'I'his is because of the relatively long stroke which permits of sufficient time to elapse when the knob Il is l released for the given acceleration of the spring II to bring about the required highvelocity. It

is desirable that the weight of this assembly be low. This is because a' body moving at high velocity has a piercing or cutting action which 50 increases rapidly with an increase of. velocity. The kinetic energy of the assembly is proportional to its mass. multiplied by the square ofits veloc-` ity. Therefore, comparatively less 'is to be gained in the mattei' of increasing kinetic energy 55 byincreasing the mass; and more is to be gained by increasing the velocity. vbecause the effect of this goes up as the square. Furthermore, increasing the'm'ass has the following undesirable 5 effect: Whenthepointil pressesthe sheetmetal k28, the assemblyis decelerated. 'Ihe force of deceleration is necessarily Provided by the sheet iron V28. 'Ihis force is proportional directly to lthe uiassanci directly to the deceleration of the lo system being Therefore,` since not muon piercing eir'eetis zo be saines by increasing the mass of the system Il, Il, Il, anda disi advantageous force is appliedtothe sheet metal Il in dcccleratinl this system, it should be made 15 as light as possible. The stroke of the device should bemade as long as possibleso thatfmaximum increase may occur in the desirable velocity. It will'alsobe seenthat, if the mass of the assembly Il. Il. Isis increased, the maximum zo velocity obtainable from a-given acceleration Ydurings. given time would be reduced if this masscwere greater. Thus. every reduction in the Marking heretoforey have been made v yin which energy is storedin a'spring. Upon pressing the punch to surface marked, the nnalpressurereleasedthespring tocause ameni- H30 ber tostrike the punch. This invention differs 55` invention, rthe punch when it strikes the sheet metal is operating at high velocity.

in which like numerals designate like parts. case, a compresion spring II' is vused seg' ve found that improvement in piercing acetfected ifthe point 2l has a rotary motion ters metalli. Two ways ofobsuchrotary motion are shown in Figs.

6 Inl'lg. thecompressionspringil' Y, with'the rotary mechanism. This rotarymechanism is ase-follows:

' w .it the bottom end-ofthe shank n.11 provide anoche: :s in which is nicahiy arranged a shank Il. 'Iheshanklspartofamembertowhichthe punchshank llisscrewedQHelical slots inthe stemfil adjacent the shank Ilyare adapted to: 5s receive the'ends of a cross pin 3l inthe shank VIl. Aspring'll normally-crees the shankll ends of slots Il. i' Y above, it will be seen that when the downwardlyso that-thepin atthe lower so devioeoiriaiisoperated, thepoinz zi enters.

. 'Iherefore, the punching operationpthejpunch has a rotary tendency which the piercing action. In Fig. 5 is shown 'another method for obtaintion that twisting action on massofthisassemblyresultsin thedecreasein effects and increase in desirable ei-l g5. im, f

rn m. ais shown another form or the inven-A this ving a reactionagainst enclosing head Il on tube I, and.apin'21on;the s tem Il. The

the punch 2i occurs at about the time that the punch enters the sheet metal.

In both forms of the invention shown in Fiss. 4 and 5. the reaction to twisting is obtained by the motion device s on the sheet metal.' This g l that the accelerating spring may accelerate the punch to a high punching velocity. 'Ihe fact that the punching assembly has low weight means l .that the force of deceleration "is lower and that 15 the sheet metal 2l will not be substantially deformed during'punching. The sizes of the parts f are arranged to accomplish these ends for given thicknesses of sheet metal.

In viewoftheabove,itwillbeseenthatthe ,o

several objectsl of the invention are achieved e and other advantageous results attained.v

As many changes-could be madein carrying out the above constructions without departing from. the scope of the invention, it is intended g5 that all matter-contained in the above description or shown in the accompnyin drawing shall be interpreted as illustrative and not in a' limiting sense. i f

I claim:

1. A sheet metal punch comprising a portion v adapted to be held against the sheetmetal, al movable punch assembly having a point and adapted manually to be retracted from saidsheet metal, and reacting means between said punch 3 5 assembly and said body portion to accelerate the punch assembly toward the sheet metal to provide therefor a substantial velocity before and as it strikes the sheet metal. f I 2. A sheet metal pimch comprising a portion 40 adapted to be held against the sheet metal. frictional holding means at the point of contact. a movable punch assembly of relatively low mass Y having a point and adapted manually to ybe retracted from said sheet metal, and spring react- 5' ing means between said punch assembly and said body portion whereby when the punch is released o it is accelerated to`attaln'a substantial velocity before and as it strikes the sheet metal.

3. A sheetl metal punch comprising arelstiveiy n Vlong cylindrical portion, resilient friction means j at one end of said cylinder, a relatively long shank in' said cylinder, a punch at one endoi said spring. means reacting between the shank and said cylinder whereby upon release `after withdrawal of the shank fromy the cylinder, said spring -means accelerates the shank and punch assembly to attain a relatively high velocity before and as thepunch strikes the sheet metal. ,5. A punch comprising a part adapted `tombe @heid stationary so sheet metal, a part remetshle 10 therefrom, a punch on said last-named part.

spring means between the retractable part and the stationary part adapted to have energy stored therein upon substantial retraction of the punch from the sheetmetal, and adapted to accelerate.

the punch when released, said punch when it strikes the sheet metal having a velocity high enough to pierce a hole through the sheet metal.

6. A punch comprising a tube, a sleeve at one end of said tube providing friction means between i the tube and sheet metal to be punched, a slidable shank inthe tube, a punch on the end of the shank adjacent said friction device, means at the opposite ends of the shank for manually grasping and retracting the shank with the punch, spring means reacting between said shank and said tube and adapted upon release after withdrawal of the shank to accelerate the shank and the punch to a high degree as the punch reaches the sheet metal.

7. A punch comprising a tube, a sleeve at one end oi.' said tube providing friction means between the tube and the sheet metal to be punched, a slidable shank in the tube, a punch on the end of the shank adjacent said friction device, means at the opposite ends of the shank for manually retracting the shank with the punch, spring means reacting between said shank and said tube and adapted upon release after withdrawal of the shank to accelerate the shank and the punch to a high degree as the punch reaches the sheet metal, and means for rotating the punch as it strikes said sheet metal.

8. A sheet metal punch comprising a body portion adapted to be held against the sheet metal. a movable punch assembly having a point adapted manually to be retracted from said sheet metal, spring reacting means between said punch assembly and said body portion whereby when the punch is released it is accelerated to attain a substantial velocity as it strikes the sheet metal, and means for causing rotation oi' the punch as the sheet metal is pierced.

9. A sheet metal punch comprising a relatively long cylinder, anti-skid means in one end of the cylinder adapted to contact sheet metal, a shank in said cylinder, 'a punch on the shank adjacent said anti-skid device, means at the other end of the shank and external to the cylinder adapted to form means for withdrawing the shank and punch from the cylinder, and an elongated tension spring, one end of said spring being fastened to said cylinder near the anti-skid device, and the other end being fastened to said shank near said manual withdrawing means.

10. A sheet metal punch comprising a body portion adapted to be held against the sheet metal, a movable punch assembly having a point adapted manually to be retracted from said sheet metal, reacting means between said punch assembly and said body portion whereby when the punch is released it is accelerated to attain a substantial velocity as it strikes the sheet metal to pierce it, means for causing rotation of the punch as the sheet metal is pierced, said last-named means comprising a groove in the portion which is held against the sheet metal, said groove having anelongated part parallel to the axis of the body portion and a twisted part, and a follower movable in said groove and adapted to accelerate along said elongated part of the groove and to twist the punch assembly after substantial acceleration and as it strikes.

11. A sheet metal punch comprising a body portion adapted to be held against the sheet metal, a movable element adapted to be retracted from said sheet metal', biasing means between said movable element and said body portion whereby when the movable element is released it is accelerated to attain a substantial velocity, a punch head slidable on said movable element and adapted to strike the sheet metal at said substantial velocity to pierce it, and means for causing relative rotation of the punch head with respect to the movable element as the sheet metal is pierced comprising means normally biasing the punch head forward in the direction of movement, and

cooperating means between the punch head and the movable element to eifect twisting during relative motion upon impact with the sheet metal.

CLARENCE E. MANGE. 

